Fetal growth of Northwest Atlantic harp seals, Phoca groenlandica

• Published in: Canadian Journal of Zoology
• Main Authors: Stewart, R. E. A., Stewart, B. E., Lavigne, D. M., Miller, G. W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1989
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Northwest Atlantic; Phoca groenlandica
• Online Access: http://dx.doi.org/10.1139/z89-305; http://www.nrcresearchpress.com/doi/pdf/10.1139/z89-305

Reproductive organs, fetuses, and newborn pups of Northwest Atlantic harp seals (Phoca groenlandica) were collected from 1977 to 1984. These data were used to describe development and fetal growth in terms of biomass and energy, and to estimate the timing of gestational events. The mean pupping date in the Gulf of St. Lawrence was March 2. After the pups were weaned, females mated and conceived around March 12–14. Suspended development of the embryo lasted until early June and implantation took place in August. Fetal mass was more useful in assessing fetal growth than were linear body measurements because it could be used for a greater range of fetus sizes and had lower variance. After implantation, fetuses grew approximately 0.10 g ⅓ ∙d −1 until they were born the following March. Caloric content and caloric density of the fetus increased during active gestation. Caloric density increased most in the last 2 months, which is consistent with an increased deposition of lipids.